Why are you mentioning the likelihood of them being added to the constitution while ignoring that one took a civil war to happen?
You’re saying you’re confused about why slavery was outlawed but abortion wasn’t when the nation was more divided during slavery. It’s because they had a civil war over it! That’s the only reason the constitution was amended to ban slavery, because of who won that war.
It’s possible that even if the nation is less divided than it was during the Civil War, it’s still too divided to amend the constitution to protect abortion.