IMHO, LISP is ok for theoretical fundamentals but it won’t necessarily get you a practical understanding of how computers work. Functional languages are more like how mathematicians wish computers worked. All programming languages are abstractions, but functional languages abstract away how the underlying hardware works in ways that procedural languages don’t.
And Java is pretty useful if you want to get a job but if you don’t want that, then there are less painful options. The difference to Python is mostly that Java often feels like it was intentionally made annoying to use. But it’s a pretty high level language, I wouldn’t call it more fundamental or basic than Python. Java wins on performance but that has nothing to do with how high level it is.
For practical fundamentals, if you actually want those, I’d recommend starting with microcontrollers and their assembly. Modern CPUs are so complex that learning fundamentals from scratch with assembly is quite difficult. But with smaller/older microcontrollers (like PIC or something) it’s both more approachable and more useful. It’s almost a shame that hobbyist microcontroller platforms are pretty advanced now too. But you can move on to C first, you can ignore MicroPython for a while if you want.
If you want a game way to learn absolute basics, there is a game called Turing Complete. It basically teaches you how to build your own CPU architecture from logic gates. You start with the basics about logic circuits and eventually build a simple CPU, and then another more complex one. I think this actually goes a bit too far in terms of fundamentals, it will take you forever to learn how to even make something write Hello World on a screen. But I guess this is the closest to how I started out. Of course for me the logic part was theory only. And the CPU I eventually learned programming first was a 6502 and not something I designed myself.