There is much more natural matter entering our atmosphere by way of dust and meteorites. This one says about 40 thousand tonnes each year:
https://skyandtelescope.org/astronomy-resources/astronomy-qu...
Granted, not all of this is aluminium but I can imagine there is more metal raining down than all man made satellites combined.
As to space junk which is matter floating on specific orbits around Earth, it does not matter much what it is composed of. If they hit each other at multiple kilometers per second it doesn't matter if it is made of wood, paper or steel. The result is from kinetic energy being released, not the composition of the bodies.
I think the goal should be to make less satellites, smaller ones and maybe also built in a way that would make them less prone shattering into multiple small parts if hit.
Less satellites -- satellites should be shared. We shouldn't be in a position where every company that decides to send thousands of satellites can do so at will. I think the number of satellites at various orbits should be limited and controlled the same way the electromagnetic spectrum is being controlled for common good. For this reason we should think how we can make as many possible uses with small amount of satellites and this I think should include some sharing schemes (the same way we share EM spectrum).
Smaller == less cross section for collisions, less matter spread in case it collides.
Less prone to shattering == further prevents or slows down any chain reactions from part of one satellites hitting another satellites.