Sigh...

This is THE original definition. Language later evolved and people started using the word meat to mostly mean animal flash. But that's just proof that language evolves over time and now it's evolving again to include broader range of food.

But in any case, I'm sure you've heard of meat of a fruit or nut.

Yes I have, but it's normally obvious from the context that a fruit or nut is being referred to, usually by qualifing the workd with either 'fruit' or 'nut', or the person holding either.

If someone asked me to buy some meat and I returned with a few apples I'd receive a Merriam-Webster dictionary to the head!

Exactly like with plant based meat, soy milk and veggie burger, right?

The original definition, as far as we can track it, would appear to be "wet".

You do use it in a more general sense in some contexts, but I completely agree with your point.