Here is a preliminary Jazz 3 City mockup.

Originally, Jazz 2 levels and tilesets were saved together as one file, with the .LEV extension. This was in the early stages of development, when JCS was still called MLLE(Multi-Layer Level Editor, not to be confused with Violet CLM's WebJCS-like project of the same name, which can edit levels of JJ2 1.00g/h, 1.10o, 1.23, and 1.24, aswell as Battery Check, and Animaniacs: A Gigantic Adventure, the two other games that use Jazz 2's engine, neither of which's levels can normally be edited by JCS).
This early .LEV-style of saving levels can be seen in the 1.00g and 1.00h OEM beta versions of the game, although neither included a level editor.
A screenshot of this very early JCS(MLLE) can be seen here.

And getting back to Violet CLM's MLLE, a little while ago, a beta version(1.10o) of Jazz 2 was discovered(It was a review copy if I remember correctly), which used J2L/J2T files like the final game, although the final version of JCS can't open these files. However, 1.10o included its own version of JCS, which can open these levels, aswell as Battery Check levels. This level editor was reverse engineered into an unreleased project known as BCCS(Battery Check Creation Station), which was never finished, although a lot of the work that went into it helped Violet CLM put together Battery Check support in his MLLE project.

We all know that Jazz 2 has all its enemies, objects, sprites, etc. pre-loaded into the engine, making level editing in JCS quite easy. In contrast, Jazz 1 saved all its sprites in specialised files for each level(SPRITES.xxx), aswell as one sprite file for Jazz(MAINCHAR.000).

The way events worked in Jazz 1 was that there were about 128 blank events, which had a lot of settings and behavioural modifiers you could change, which would apply to all instances of that event in the level. When you set all these settings right, they become specific events(Although some events(I forget which ones) should be left blank, as they function as things like drawing the tile in front of Jazz, making the tile intangible, etc.). This is complicated to get working and understand, but it means that Jazz 1 had a highly versatile engine(Sonic With A Gun showcases a lot of the stuff JJ1 can do when pushed).

One of the things you can modify about each event in JJ1 is its name. If you open the final level of Episode 6 of Jazz 1 in J1E, you can see that the developers named the final boss "Fucker".