Are you reading your own posts? You just said it was NOT some curved "thing". Things people can visualize, non-things people cannot visualize.Everyone got that memo? We are not allowed to use diagrams to visualize space-time anymore!
If something moves along a line in space, you can omit 2-space dimensions, and visualize a 2D-spacetime. Works fine for me, and you don't have to use it, if you don't like it.
Are you reading carefully? Omitting 2 space dimensions reduces the problem to an analogy. Just like putting a stick figure on a sphere. It's just an analogy. If it were the "real thing" it wouldn't be an analogy and we'd be able to visualize "the real thing".
Go ahead, show us 'a' 4D space-time?