My only guess why Peter liked MJ was because originally we know in Homecoming he had a crush on Liz but when she left I guess he started to have feelings for MJ
Where did you get that idea from? I never once thought that MJ was only interested in Peter just because he was Spider-Man. That's always been more Black Cat's hangup then MJ's.
No. MJ has always been in love with Peter from Homecoming way before she ever knew that he was Peter, that a core's part of every MJ character is that She love Peter way more then Spider-Man.