Someone said that Christianity is second-hand Judaism. Do you agree?

Yes it is. It is a copy of a copy of a copy, every bit of it borrowed from previous Pagan and secular sources. It is truly a 2nd hand religion, and it is a beater to boot.

Christianity is definitely NOT 2nd hand Judaism as Christianity violates nearly every core Judaic teaching and belief there is with the sole exception of the messianic myth. Christianity is in fact a 3rd or 4th hand paganism twisted around a stolen and reworked Judaic myth. The theft of a single mythical note doesn't entitle Christianity to claim any relationship to or foundation in Judaism.

It is the obvious opposite of that (for many) Judaism is an unrevised Christianity.

If done properly, Christianity is a rejection of all foolish old practices, like burning gays and witches, keeping child sex slaves, crucifying people for saying I am God, when the old testament says you are gods, all of you, sons of the most high. That sort of thing. Jesus was an Antitheist, or perhaps he believed in God, but wanted to believe that God was nicer than these monsters.

No its not Judaism at all. Some of the most basic Jewish requirements are completely and deliberately avoided.

No. Christian Catholic churches predate the rabbinical Judaism practised today by a couple of centuries.

Religions just evolve as time passes, and Judaism evolved into Christianity and Islam.

Every religion that exists today has been influenced by other religions. A simple fact. None of them are "original", and, yes, that means none of them has been "revealed" by a divinity; they're all human constructs.

Both Jews and Christians are rude.

Just another nonsense BuyBull cult. That's ALL it is.