Honestly even this is overkill for 90% of it's use in Slack. 90% of the time all I want to do is quickly reply to a message for the sake of context. There is no need 90% of the time to create an entire thread around a reply, just a simple yes/no answer to a question and showing the connection of that yes/no to the original ask is all that is needed.

Look at Discord, NOT slack as a point of reference for Replies and Threads.

Please please please do not emulate Slacks' terrible implementation as is, Discord is infinitely more useable and better of an experience

And what do you think about adding the ability to share any message to chat instead of copy/paste the link?

I would think about this. This feature in Slack can cause a lot of confusion. I would suggest taking a look at how Glue handles it https://gluegroups.com/ everything is a thread, no channels. You can create a thread, title it and add whoever you want to it and then any message in that thread is only going to those intended so you wouldn't need to reply to the channel and create unnecessary clutter or ping people who were not involved in a certain conversation. There entire value prop is to get away from the inefficiencies of Slack channels and I think enabling "reply to channel" would be a net negative.

Can you make sure not return error if clickup for threads is turned off? Make it hidden in case threads is turned off.