OK, this takes several explanations.

First, mechanical calculators were also called computers way back in
the 19th century.

Next, the first programmable device invented by Charles Babbage was
called the analytical engine. The programmer was said to be Ada
Augusta, Countess of Lovelace, daughter of Lord Byron. [1842]

As far as the modern computer is concerned . . . the first time the
word computer appears in print is in 1945. The term ENIAC means
electronic numerical integrator and computer. The term was printed
in the following title . . . “Description of the ENIAC and comments
on electronic digital computing machines”. J. Eckert et al. Note
that both computer and computing are in use as of 1945.

The term electronic brain does not appear until 1946.

The theoretical precursor to the modern computer was the Turing
machine described back in 1937. It was named after the mathematician
Alan Turing.
------------------------------
1945 - Grace Murray Hooper (Admiral USN) pulls a dead bug [moth]
from a broken computer relay on the Mark II computer at Harvard
University. She later glued the bug into a logbook of the computer
and this very first bug is still kept in the National Museum of
American History of the Smithsonian Institution. BTW, Continual
cleaning of the relays was referred to as "debugging" the computer.