Yes that chainring is noticeably worn. When comparing the two photos, focus on the top and you can see the tips lean to the right in one shot and to the left in the other shot. Flipping between them looks like someone waving.
That, along with the slack test shows there is wear. Since you're getting chain slip, that wear shows its time for a new chainring.
As for Aluminium vs Steel vs other materials like carbon fibre, well its all a cost/weight/durability triangle. (the old Pick Any Two conundrum)
A related aside... If you never ever use the inner chainring, this might be a good time to consider a 1x setup so a narrow-wide single chainring.
Personally, I've seen chainrings in much worse state, working perfectly well. It comes down to your power, your chain state, and other variables like chainline/angle etc.