I'm almost certain these little deja vu moments are snippets of 'past lives'
No, they aren't. They're memories that we've forgotten, frequently places and things we've read about or seen in films and TV programmes.
Actually that's not what deja vu is at all, and they've never actually proved what it is or isn't, only theorised. The one I think makes most sense is that, when your brain processes "there's a house" it stores it in your long term memory instead of the right now short term memory, so you feel like this happened ages ago instead of right now.
I'm certainly open to the fact we could have had past lives. There is no evidence to rule it out, and in fact, the evidence science does give us is that energy can never be destroyed or created, only changed from one form to another. So I tend to think people who outright dismiss these things are as naive as the people who outright dismiss the existence of aliens.