Thanks for the clarification. There is a lot going on with the new platform, so we definitely need to provide more guidance on where things are and how to get around.
As for a Search function, that's definitely available in the form of a magnifying glass, right next to your avatar and hamburger menu (three horizontal lines).
If you search "rainbow", your thread is the first search result.
As for finding your own stuff, whether it's a topic/thread you created, or a reply you made, those can all be found from your user page, under the Activity section. To get there, click on your avatar in the top right of the page, then click your username, and the select Activity.
You'll see a list of your account activity, so topics/threads you created, replies you made, likes given, and your bookmarks.
Your INGOT'S RAINBOW thread will be listed there when Topics is selected.
As for capturing a user's attention, Discourse displays as much, or maybe more, than vBulletin did from the forums homepage, minus some thread or post-specific information. So I think we're fine giving members different avenues to explore. Something vBulletin didn't do was give members immediate access to Unread threads and posts that they are contributing to or watching.
We could have absolutely continued on the old forums. But why use something less secure, less stable, less configurable, slower from a performance perspective, more expensive to maintain both from a financial and human capital perspective, with less features, and less room to grow?
Please explain. You've said it several times with no other information detailing exactly what you mean.
Yet you are still here. What is your motivation to providing feedback and continuing to contribute?