I'll give a different perspective on this:
Do I like who I am? Do I love myself? Do I completely accept who I am? (Please note that this addresses us, not our behaviour).
If I can answer those questions in the affirmative, then I have to note that to change any of my past is to change who I am. Every single experience I have, whether "positive" or "negative", has shaped who I am. I may not want to repeat those experiences, but they are a part of me, and to reject a part of me is to reject myself (we are not divisible).
Again, another perspective: Does everything happen to us for a purpose? I would say no. Does everything happen for a reason? Yes, but we don't know what it is. Oftentimes it's the laws of physics:)
Events do not happen to me for me to learn from them. They are just events. I experience them and decide what they mean to me - I am responsible for that assigned meaning. If I see a little kid hit by a car, it is the height of narcissistic ego to think that that tragedy happened in order to remind me of the transitory nature of life. But if I witness this tragedy, and I do not take the moment to remind myself of the transitory nature of life, I have missed an opportunity to derive whatever positive effect that tragedy might have conveyed.
So, no, IMHO the universe is not conspiring to teach us lessons. The universe is providing lessons 24/7 - and sometimes we pay attention.