Even the most hardcore gamer wouldn't load all their favorite games onto their hard drive and then fill the desktop with game icons.
There's something called steam, where you can play or download at any time.
The hard drive of a computer has more important uses.
The same applies to human memory; theoretically, even if you have decades of complete life memories, you would still forget where you put your phone.
The brain does not save all memories but only retains extremely memorable snippets, such as getting a mixed doubles scolding from parents for childhood mischiefs, failing to confess to the school beauty, losing a phone, a wallet, or an ID, or being verbally humiliated by the boss at work.
If accumulated enough, it turns into konjac jelly...
Knowing who you are, and being unable to recall past experiences, actually isn't contradictory.
It's normal to forget what your elementary school classmates looked like when you're in college.