Properly Balancing a Level

I am trying to get that first level of my game “just right” where things start out real easy, get moderately more difficult, and climax with a few really hard waves. It’s a tower defense, and I would really cherish some feedback on my current first level
playable here. It doesn’t have much of a tutorial, but if you’ve played a tower defense before I’m sure you can figure it out really quick (actually just somewhat sure about that).

The objective is to upgrade the top left sewage pipe to max capacity (lvl 18) and to keep debris from floating into the drain.

While I get the gist, I couldn’t really get started, beyond spending my money, and getting a bit confused about the goal.

Could you provide a set of instructions, perhaps just a bullet list of the first 20 things to do in-game, as I reckon that’d help me get further into it.

There’s a sewage pipe in the top left of the map. The goal is to upgrade it to lvl 18. Each time you upgrade it the spawned debris grow in strength/number.
You lose lives when debris gets stuck in the pipe or when debris goes down the drain.
The first thing to do is either set up an acid sprayer or a garbage-can + pitch fork combo to defend against early waves from getting to the drain, then build up from there.

I am getting the impression that the game is not easy to figure out at all and I’ll need to have a moderately in-depth tutorial XD

This game definitely needs a tutorial. It might be a good idea to make a bunch of smaller challenges, that introduce one or two game mechanics at a time.

Yeah, definitely a bit more guidance would be useful to first time players.

I managed to get further playing it a few more times, but it took a lot of trial and error.