I can explain to you how two people can exist in one. Your father is also a son.

I don’t think there’s a point answering the first as it relies on the second.

Your assumption is wrong. I deconstructed my beliefs and ended up switching denomination because of it. And as I have said earlier - albeit to somebody else - the genetic fallacy doesn’t hold any water. Most Christians I hang out with actually are converts themselves, including my closest brethren. I could also say “if you grew up in Saudi Arabia, you wouldn’t be an atheist”. Doesn’t legitimise or delegitimise your beliefs. It depends on if you questioned your beliefs. If someone was raised atheist, decided to examine religions and stuck with atheism in the end, I don’t think it would be fair to say that they were just indoctrinated as an atheist and discount their atheism. I questioned my own beliefs and they changed slightly, but I saw the rest were well grounded.

Similarities in other religions predating Christianity aren’t quite the same. Sure, some themes exist, but Christianity is quite original in the narrative.

The translation of the Bible I use is the English Standard Version, which is translated from copies of the original greek manuscripts. Textual criticism is important. While we don’t have the originals or even first generation copies, we have several new testament manuscripts spanning parts of Asia, Africa and Europe. And they all say roughly the same thing. Mistakes and variants (usually spelling errors, misplaced verses, at most a different or new paragraph) can easily be weeded out by looking at the majority of manuscripts. Thankfully - unlike most records from that time period - we have an abundance of new testament manuscripts to work from. If you have a Bible with footnotes (specifically thinking about my ESV here) it clearly states where there is a variant and we can’t be sure. Such as John 8:1-11, the doxology of the Lord’s prayer or the ending of Mark’s Gospel.

Hinduism and Buddhism (like most religions) both try and preach a Jesus. They both adapted to Jesus trying to make room for him. Buddhism compromised and claimed Jesus was a Bodhisvatta (Jesus Himself didn’t - He claimed to be the One True God) and Hinduism tries to depict him as another rendering of god (Jesus said He was the only way).

Proving the Trinity without first proving Christianity is pointless;

The best place to start when looking into any religion is Jesus - He forms the biggest and is incorporated in basically all of them, so He’s a good place to start. If Jesus is who He said He is, then what He said is true.