The concept looks more Homeworld 2 than Homeworld 1 to me. Though there is some form and features, these seem somewhat monolithic overall, and therefore make me think a lot more of HW2. The middle two remind me of Keepers, or perhaps more precisely, a mod Progenitor ship with heavy Keeper inspiration:
So I guess I could see the top 3 being some kind of Progenitor utility ship, but the bottom one seems more vaguely Hiigaran. I can see some Kushan in it like Pouk, mostly because of the engine. And I agree with him that the second one could be easily adapted to a Taiidan cruiser of sorts, particularly if the circular elements were taken out and replaced with some kind of bulky, blocky protrusions.
I think I like the top drawing best, but I also agree with Pouk that it isn’t complete as it is. I think if you added a whole other segment to the ship under the existing bit you could make something pretty interesting looking, though lool, I’ve no idea what.
Furthermore I’d like to say that I think this is a superb idea for a thread! I’m very glad you thought of it, and I thank you very much for expressly wanting to include me in it