That's not really your point, though - your point seems to be that everyone could make more character concepts with 3.5 than they will be able to with 5.24. Now, leaving aside that we don't really entirely know what we'll be able to make with 5.24, I think it's a bold claim, and I think you're going to get a lot of pushback. In particular, when the designers, who probably ought to know, have claimed otherwise.
(And taking into account that you seem to be discounting any 5e builds that you couldn't build with 3.5 and only focussing on builds that you DID build in 3.5 that you can't, for whatever reason, in 5e.)
I admit that I am not anywhere near as impressed with 3.5 as you are, but I don't really have any skin in this game. As unbiased as I can try to be: I still think you're mistaken, and seeing 3.5 through rose-tinted glasses. (I'm glad you liked it, though! It was a very popular version of D&D, you're in good company, I'm sure!)
Eh, you know what, just for fun.
Using the OneDnD playtests as a baseline, I am going to go for some maximum number of combos at level 1, ignoring skills and feats.
Classes: 12
Subclasses: 4
Sample Backgrounds: 18
[technically the number of backgrounds are ridiculous, because the default is custom, but I'll just go printed]
Distinct Species: 9
What if we do sub-species instead: 28
So, that is between 7,776 and 24,192 options depending on how you count things.
Again, just for fun. 3.5 PHB
Races: 7
Classes: 11
Add in Cleric Domains: 21 options, can pick two each... I think this is 231 combinations.
Wizard School specialization: 9 options base (don't specialize, plus each school) each specialization gives up 2 schools except Divination, which is 21 combos each time, so.. 169 options?
How do I even calculate this... let's take 7x9 = 63
7x231 = 1,617
7x169 = 1,183
So that is between 77 and 2,863 options, depending on how you count things.
Now, I could try and add in skills. It is a little bit of a nightmare, but I could, same with feats... but seeing that the low-end of 2024 is looking to have double the high-end of 3.5? I don't think going through all that would make a huge difference in the end results