Great question you gave right now. First of all I switched from Pearl to Amour because of the great design Serena have. I liked Dawn so I would like Serena as well if it was only about her design. However the fact that they know each other from their childhood and that Ash saved her before isn't meaningless.Here's an interesting question for you people
If Serena had a different role, (A.k.A, she never went to the summer camp, A.k.A no childhood memories, no saving and definitely no crushings involved. She's a different person) would you still ship amourshipping like you currently do? Why or why not?
Before I come into conclusion I say that those events in her past likely affected her person. I mean she kept his handkerchief for all this time and wanted to see him again. Was very excited to meet him again which eventually led her to fall in love with him. Not puppy love ignoring all his flaws. But healthy one when Serena accepts him as a whole with all his assets and flaws.
Well she never liked that camp and there is a chance that would isolate her from people. But we won't ever find that out.
Probably she wouldn't start her journey at the moment she did. Unlike Ash or Dawn she didn't start her journey right after she turned 10. She was training Rhyhorn Races already so she was after her 10th birthday. Ash was the reason why she decided to leave home and pick her first Pokémon. She wanted to meet her childhood hero. They probably would never met.
So concluding. If those event in her past never occurred and if she didn't fall in love with Ash but assuming she would travel with him anyway I would ship them anyway however not as much as I do now.