Old argument.
See the Dead Sea scrolls and various ancient manuscripts.
You forget (or choose not to acknowledge) that the Holy Spirit is here on the Earth. He is more than capable of protecting the integrity of the Word - and has done so faithfully for millennia.
Catholicism rejects that and embraces the traditions of man for sure, and has for centuries persecuted the true Church. The reformation was pivotal in breaking that control off of believers - and changed the world in doing so.
Let’s be real though - you’re just rewording one of Satans favorite lines - Has God really said?