He’s the one who properly started computer theory, I suppose

Babbage invented the computer, Ada invented the programming language that would be used to program it. She even wrote the first ever bug in it.

https://twobithistory.org/2018/08/18/ada-lovelace-note-g.html

"In her “diagram of development,” Lovelace gives the fourth operation as v5 / v4. But the correct ordering here is v4 / v5. This may well have been a typesetting error and not an error in the program that Lovelace devised. All the same, this must be the oldest bug in computing. I marveled that, for ten minutes or so, unknowingly, I had wrestled with this first ever bug."

While Ada Lovelace did not actually help inventing the Analytical Engine, she was arguably a greater visionary than Charles Babbage, who, as I understand it, mostly thought of it in terms of calculations.

This is what she wrote in 1842, one hundred years before the first general purpose computer was actually built (Babbage's Analytical Engine was never built):

[The Analytical Engine] might act upon other things besides number, were objects found whose mutual fundamental relations could be expressed by those of the abstract science of operations, and which should be also susceptible of adaptations to the action of the operating notation and mechanism of the engine...Supposing, for instance, that the fundamental relations of pitched sounds in the science of harmony and of musical composition were susceptible of such expression and adaptations, the engine might compose elaborate and scientific pieces of music of any degree of complexity or extent.

babbage: the calculator lovelace: the programming language turing: the computer science

The first functioning programmable computer was Zuse's Z3.

Blaise Pascal was the real OG: https://en.wikipedia.org/wiki/Pascaline