Jews and Christians used ‘Allah’ (as it appears also in Arammaic... the prvalent semitic language in the ancient Middle East) BEFORE Islam.
The name of the pagan deity of Mekka was ‘Hubal’. Of course the Arabs called him Allah as he was their god.
*Aramaic
“The name of the pagan deity of Mekka was Hubal. Of course the Arabs called him Allah as he was their god.”
==
He may have been a local fave, just as Diana of Ephesus was - but still just one of the Arabic pantheon.
Here’s some background:
http://wathanism.blogspot.com/2011/11/deities-beings-and-figures-in-arabian.html