there are several other approaches to locking a cell. first, you could put the data in a cell somewhere else. or you could make that row/column 0 units in size so it doesn't even show up. You could also use data validation and make it the only value in the allowed list.
If you're only worried about accidental editing and not malicious editing, you could put ALL your user inputs on one sheet in one place annotized and formatted as best for them, and do all the calculations etc on another page that draws its data from the input page. And then maybe have a third sheet that is all the output?
Using data validation lists alone could be the solution to your problem, preventing people from making invalid entries? Data validation can allow one selection (say to "fruits" to change the validation list in the next column to only include fruits as selectable options in the popup etc.
