Welcome to the Tableau and its Community! I hope you to have a great time using this amazing tool.
Regarding your concerns, I am no layer nor I work for Tableau so it is hard to give a 100% sure answer on the terms. From my understanding on the Ownership item you added I only see there the ownership of Tableau Public software (not the data) belonging to Tableau.
Personally I use Tableau Public as any social media site you may use around. I am only able to add data/text/pictures/videos because the tool was made available for me by the owners. But I can go and wipe all my data off from those sites if I want. Same applies to Tableau Public IMO.
Ciaran Crean may be able to help you as she works for Tableau and coordinates the Forums too.
I hope this helps
Brilliant, thank you Rodrigo for taking the time to respond to my query. I’m very grateful.