This is an interesting question.

By default, 吃的人 would mean 吃xxx的人， like 吃肉的人. Example, 这东西吃的人很少 means 吃这东西的人很少.

If you truly want to denote 'a person who someone eats', you could say '所吃的人' or '所吃之人'.

One of usage of 所 is to precede a verb to indicate the following object is the receiver or accepter of that action. In this case, 所吃的人, 吃 is a verb and 人 is the target. So, 所吃的人 clearly denotes 'a person who was eaten'.

Here is some examples:

他所吃的人 // the one who he ate;

你知道他所吃的人是谁吗？ // do you know the person who he ate?

This is an interesting question.

By default, 吃的人 would mean 吃xxx的人， like 吃肉的人. Example, 这东西吃的人很少 means 吃这东西的人很少.

If you truly want to denote 'a person who someone eats', you could say '所吃的人' or '所吃之人'.

One of usage of 所 is to precede a verb to indicate the following object is the receiver or accepter of that action. In this case, 所吃的人, 吃 is a verb and 人 is the target. So, 所吃的人 clearly denotes 'a person who was eaten'.

Here is some examples:

他所吃的人 // the one who he ate;

你知道他所吃的人是谁吗？ // do you know the person who he ate?

On top of that, if you say 吃的东西(食物)， it would mean 所吃的东西(食物)--something（food） that was eaten. Like, 我们吃的东西==我们所吃的东西==something we eat.