Yes but also no. Marty and Doc befriend eachother at some point which is why Marty travels back to meet past Doc. Because they are already friends in 1985. Not because of the snake effect, youre getting ahead of yourself. Only thing is that he created a new timeline where 1955 Doc meet future(1985) Marty before he originally befriends him but this would had happend regardless. Only difference in the new timeline, Doc re him

@ken there is a logic in the very movie itself. You say time travel logic is not real but in the movie they explain the whole time travel logic FOR the movie. I mean they have their own logic which works. The movies logic is pretty bulletproof for me and thought out. I agree with everything else you said