I could not collect them. But the whole premise is supposed to be about survival so it would be immersion breaking deliberately not picking up ammo and health kits.
The whole series is REALLY bad when it comes to survival aspects - just like a lot of other games. For instance, stirring up dirt which is radioactive across that area will land on your clothes, weapons, etc. You should
always be radioactive until you clean your gear and most certainly don't get better after drinking Vodka... This is a serious "bug of the plot" for both Stalker and Metro series.
Weapons jamming is nice, but way, way overdone and someone that knows its way around weapons (and our guy should), will know how to keep them clean, change a barrel, etc.
Food, water, drugs (as in medicine), ammo, all of these should be plenty since each individual should have enough of them to survive there. Taking a couple of them out should give you plenty resources.
Bottom line, they're using the wrong things to build the survival aspect (and poorly), instead of trying to adapt real life elements to the game.
In my example, I died a few times, sure...but it was ultimately pretty easy to kill them off and proceed. I was honestly expecting to give up and go back down to Stalker difficulty but it really wasn't that hard.
The game felt REALLY hard at the start...but at this point I'm starting to feel like Rambo which is surprising.
Is pretty normal. Other games call themselves "RPGs" or "looter shooters" and just use levels (aka progression inflation) to basically keep you at the same spot, falsely giving the impression of progress.