“That wasn’t “orthodox” Christians.”
Yes, it was.
“Catholicism is a perversion of what “orthodox” Christians believed.”
No. Protestantism is a perversion of orthodoxy. That’s why no one ever heard of it until almost 1500 after Christianity began.
“The apostles were the “orthodox” Christians.”
The first ones. They passed on the orthodox faith to us. Your religious ancestors, all heretical Protestants, gave up that faith and embraced the new beliefs no one taught before in orthodoxy. That’s why even Protestants like Alister E. McGrath can talk about a novum being introduced to soteriology by Luther.
“The Catholic Church has added to and polluted what they taught.”
No. Protestants created a new gospel that is automatically false and have attacked the true faith ever since.
Well then prove that they passed on the teaching of the assumption of Mary.