What would be "attractive" about starting a religion that would ostracize you from your current religion, even put you in direct conflict with your old religion, put your life at risk(still the same today) people must of heard about Jesus, some must of heard him speak, he must of inspired many(I mean He has inspired billions since and they didn't even know Him, not for self gain, or an easy life the opposite). You don't seem to get it, there is no advantage of following Jesus' teaching unless you truly believe they're true, and after reading through both testaments, it reads like one book. It is divine imo.
Matthew 7:13-14
This does not address my point. I said nothing about anything being attractive, so I don't understand why you introduce this idea, and put it in quotes as if it is something I said.
The earliest Christians would have been opposed - and in some quarters reviled - as heretical, no doubt, but that is irrelevant to consideration of what techniques, arguments and supporting stories they might have resorted to, to gain converts. And they
were strongly motivated to gain converts, as Jesus had issued strong instructions on that point. In fact by claiming that OT prophecies had been fulfilled, they would be arguing they were not being heretical at all, but were simply good Jews who were in possession of a new insight, that the Jewish Messiah had actually arrived, as foretold in Jewish scripture.
I don't necessarily suggest a coordinated, cynical attempt to make stuff up. What can happen is rumours start or ideas occur to people, and these can thus become part of a folklore, and they can be adopted without there being much scrutiny of whether they are really true or not.
The virgin birth is a classic. How could anyone have really
known that Mary was a virgin when she gave birth to Jesus? It's a very intimate piece of information. The only people who would really know would be Mary, Joseph and Jesus himself. Who, among these 3, would have talked about it with the evangelists? Or if not with them directly, then with whom? If there had been an actual conversation, surely that would have been quoted with attribution to the speaker, to make the story convincing. Yet there is no first hand account of where this information about Mary's virginity came from. It is just stated, with no supporting story. One has the suspicion therefore that this idea could have become believed by people predisposed to believe - and became retrofitted to enable a claim that an OT prophecy had been fulfilled.