It is another reason why I think proficiency should replace ability score if it exceeds your ability.
Baboon: STR 8 (-1), Proficiency in Athletics +5 or 6, total modifier should be +10 or +12 id you "double-count" proficiency since it is better than ability.
Yeah, the game replaced that with 'climb speed'. You probably remember that, In 3e, climbing creatures got insane bonuses to climbing if they were natural climbers (+4-+10)
Also, that picture looks cool. So, what's the DC of that piece of rock?
At one time I had a chart of all the levels and what DC they were. 5.5 (DC 5) being the easiest -technically, 5.0 but I wouldn't require a check for that - and 5.16 (I think it's, technically,
5.15c - they go a,b,c,d before going to 5.16) being the hardest (DC 30)
I was climbing/working on 5.12s before I got married and had kids and moved to a place that had no access to good climbing.
level 1 to 4 are hiking and mountaineering.
Here's a break-down of climbing ratings
Edit: Level 4s could require checks depending on the situation...loose rocks, high altitudes etc...uneven terrain. It really depends on the story/narrative, So it doesn't perfectly scale.