WillLem and I did this challenge for Lemmings Redux in discord just now. We didn't actually play every level, just ones that seemed most in need of checking whether the starting number of lemmings would make a difference. Our results...
Redux - Gentle
"Only floaters can survive this" already drops you to 10 lemmings, and 3 are lost in "Tailor-made for blockers" and 2 in "A task for bombers".
"Lemming toast", starting with 5 lemmings, our best result is 4 saved, which is also the overall result for the rank.
Redux - Quirky
Only a single lemming can survive "Take care, Sweetie", but fortunately that one lemming makes it to the end.
Redux - Zany
Taking existing maximum saved records (https://www.lemmingsforums.net/index.php?topic=4612.0) into account, 82 lemmings reach "Four Play". This is normally a 100% level, but when starting with 82 lemmings, one has to be a blocker-bomber to hold the crowd back while another builds over the gap.
"The North Poles" then has to be tackled by a very non-standard solution with no crowd control at all. My best result is 54 lemmings saved.
Redux - Manic
Only 10 lemmings survive "With a twist of lemming, please", and 5 of them are killed by the normal solutions before hitting "POOR WEE CREATURES". It's impossible for the floater to construct a landing platform before the other four are all killed, so there is only one survivor -- fortunately it is possible to get through "Temple of Love" with a single lemming.
Redux - Lunatic
"Private room available" only has room for 10 lemmings; "No hurry, relax" has the same problem as "POOR WEE CREATURES"; and with only a single lemming and no destructive skills except bombers, there is no way to get past "The Steel Mines of Kessel".