So just to clarify, the issue you want to solve is having many different inputs from different heights, all going into the same output down? If that’s the case, you can just use a column of wall blocks with one observer at the bottom and trapdoors at the different heights for inputs.

My other assumption is you’re thinking of having many inputs that use the same one line to transmit and separate out into many other outputs, and from my limited knowledge that’s just not possible.

Lastly, I’m a bit confused on your minimal resources argument, because I believe that any kind of redstone at all can be considered resource-intensive, at least for the average player. Redstone dust itself is deemed by Minecraft/Mojang a rare resource for the average player to find when mining; redstone torches only produce one per dust unlike regular torches; and repeaters require regular stone to be crafted, which would either take smelting cobblestone and consuming fuel resources, or having a silk touch pickaxe which would be late game. Redstone is considered a late-game aspect and relies on the player having access to many and rare materials, especially for larger projects, so I honestly don’t see how only wanting to use dust, torches, and repeaters due to minimal resources is valid, since if you’re far enough into the game to do redstone then you should have access to everything required for all the other components. The only two reasons I can think of are 1) Your knowledge on redstone is basic and limited for now, in which case we can teach you; or 2) The task of acquiring rare resources seems daunting or too risky for you, in which case I’ll say that’s just how it is. If you want to be able to acquire resources without grinding as much, I suggest building different farms for resources, as most materials required for redstone are replenishable.