Run the tile vertical

I think I would want to get that stuff out of there and take it down to the studs and start over

You need to demolish all of that and start back one step at a time with the proper waterproofing. That is a complete hack job right there.

I think they are right, you are going to spend a lot of money for tile and labor - make sure the base of the project is stable.

I am not a pro but even I can see this is NOT ready for tile. Don't just skip proper prep so you can get to the fun stuff i.e. Tile. If you tile over this as is you will soon be ripping it own anyway to take care of mold and water damage issues. It would help to see the tile you are considering before we offer advice on how it should be laid.

Oh, I am so disappointed to hear that. This house was originally built by Lennar and this is the tile they laid. Thank you so much

For the amount of time it took to remove all of those tiles the entire shower and tub deck could have been demoed. I hope the shower pan liner wasn't punctured or it will all be for not.