How did the Abrahamic religions start?
Basically, there were a number of polytheistic religions in the area, pumpkin, and it evolved from those. There's some interesting speculation about the relationship and shared content between the Abrahamic religion and the monotheism of Akhenaten in Egypt, for example. https://en.wikipedia.org/wiki/Akhenaten
What religion is older than Abrahamic religions? When did Abrahamic religions begin?
Most Eastern beliefs, such as Hinduism, Buddhism, Taoism, and Confucianism are older than the Abrahamics, but Zoroastrianism is a belief older than the Abrahamic god, and much of the stories from the Old Testament are taken from the stories of Zoroastrianism and the Mesopotamian religions, and the text the Enuma Elish. I can't say for any real certainty when people started believing in the Abrahamic god, but in the first two books of the Bible, god refers to himself in the plural; even the first commandment suggests that when God says, "Thou shall have no other gods before Me." Monotheism was introduced by Zoroaster, and incorporated into Judaism later on after the Abrahamic god, so there was an overlap. But as long as there has been man, there has been religion, superstition, and the supernatural. Neandertal man is believed to have had religion, as he was buried with care, in the fetal position facing a certain direction with tools and food, and often with a spouse or other people, as if to say that he would need them in the afterlife. Cave paintings suggest animism, and archaeologists found a snake idol last summer that dates back 70,000 years. The archaeologists believe man thought the snake was immortal, because when man found the shed skin of a snake intact, he probably thought the snake was reborn. So in this endeavor you're making the logical mistake of the genesis fallacy, that the earliest religion is the correct one or that it would disprove any others.
Which is the first Abrahamic religion?
Judaism was the earliest extant Abrahamic religion. At an academic level, we could point out that the Hebrew predecessor religion was Abrahamic, but this polytheistic religion no longer exists. The Samaritans adopted a primitive form of Judaism and could be considered the next Abrahamic religion to exist.Christianity and Mandaism appear to have developed out of Judaism in the first century. Islam arrived in the seventh century and then the Bábi and Bahá'í religions emerged out of Islam.
How old are the three Abrahamic religions compared to the oldest religion?
What do you consider to be the oldest religion? Jews date their calendar back to about 5770. Muslims only go back to 1431. Those are the current years. Christians go back to to about 300 CE.when Xtianism was recognized by the Council of Nicae (spelling). Egyptian timeline goes back to about 5000 bce. Babylonian timeline goes back about 8000 years.
Is Satanism an Abrahamic Religion?
If Islam qualifies... it would be reasonable. The Bible would say no to both. Islam disagrees with the word of God as does Satanism making both religions false.
Why is Hinduism older than the Abrahamic religions?
One reason why ‘Hinduism’ is old is that the old religion called Hinduism has more-or-less nothing in common with the modern religion called Hinduism. The Vedas (written down c400BCE but much older in oral tradition) barely mention Vishnu (5 out of 1028 hymns) and major on gods like Indra and Agni that are all but ignored now. If you allow any vague belief in some gods to be called Hinduism, and that seem to be the general view, then it is old indeed.However, so are the predecessors of the Abrahamic religions by the same token. What Abraham believed was nothing like what the Jews came to believe - not least that God would order him to ritually kill his son. Until well after the exile Jews, believed that many Gods existed (but they had signed up with one only) - Solomon raised pillars of worship to many gods (1 Kings 11: 5–7). So these beliefs (as other replies state) go back into the dawn of time too.The question’s presumption is a little misinformed and I suspect seeking to boast about Hinduism.
Who really was the oldest person to have ever lived? Abrahamic religions have their poster boys, but are they a myth?
The person who lived to the longest authenticated age was Jeanne Calment (1875–1997): 122 years and 164 days. Far greater ages have been asserted for others, but verification is lacking.
Abrahamic Christianity is the youngest of all the Abrahamic religions, which means that they also share many of the same beliefs and scriptures. Why do Abrahamic Christians boast that they have prophesies of the end times while the others do not?
I don't know that I'd agree with your choice of terms as to "boasting" of having the end time prophesy, nor that Christianity is the youngest of the Abrahamic religions. I am certainly not a Biblical scholar -- just a common guy on the path to More Light -- but my understanding is that the Christian view of the end times is based on prophesy resulting directly from the life and teachings of Jesus (found in the New Testament). Jesus changed our understanding of parts of the Old Testament, and the New Testament and its end time prophesy is not accepted by most Jews (who generally believe Jesus was not the Messiah) and not fully ascribed to by Muslims due to belief in their later Prophet. Let me also venture into an area where I have even less knowledge in hopes others will jump in and explain further: In contrast to the assumption about the other Abrahamic religions stated in your question, I believe (1) the Jews also have prophesy and beliefs as to the end times, which they believe is the time when their Messiah returns; and (2) Muslims also point to prophesy of the end times when their Mahdi will appear and, with Isa (Jesus), will triumph over the Masih ad-Dajjal (false messiah). I stand ready to be corrected and welcome further insight.