Bought amaryllis seeds online from China. Seedlings definitely not amaryllis and have no respond from seller so please if anyone can identify seedlings? What is this?

I suspect member of Caryophyllaceae like Dianthus species, flower will confirm ID of course.

I thought so myself but no. These plants seem to just grow on in length and no sign of flowering. Have Dianthus in my garden and see a bit likeness in leafs but would say no

hmm, I can see...
The other plant I have experience in the past that could look like this is Gypsophila (G paniculata). {I love experiencing on growing non tropical in the past} they just look like that, never flowers in tropic for me.
And Gypsophila is also member of caryophyllaceae... (perhaps thats why it similar). if you can be patient, you can wait. G paniculata will flower the second year usually (????...)

Might be. Problem is I don't know how to treat these plants. Their base is very very thin and fragile looking while it grows on(foot long). It does not look to try and climb up but just falls down and grows in length!

To my eyes it looks like the plants are etiolated due to low light, you can try to gradually move plant to more bright light area. I can't help much on growing advice of non tropical in nontropical climate
hopefully other will chime in soon both on ID and growing tips

They get about 3 hours direct sunlight

Reminds me of Diodia (this is one of several species in the genus, no idea which kind one might receive via seed from China.)
Virginia Buttonweed (Diodia virginiana)

Did they ever flower?
What were they?

Must have been weeds! They flowered a small white thing

Could Eclipta alba or E. prostrata be possibilities?