If Ты look at Lily and James Ты notice they are very similar to Harry and Ginny.
Ginny has red hair and brown eyes. Harry has dark hair and green eyes. Switch them around... Ты get James and Lily! Lily has RED hair and GREEN eyes. James has DARK hair and BROWN eyes.
"I never really gave up on you"
Ginny had a crush on Harry. And James had a crush on Lily (mentioned by Snape, he did ask her out).
Both Lily and Harry showed no interest, but at some stage they fell for them.
Apart from that there is nothing that shows they're very similar.