There have been people that have bought mid-range bikes and added higher quality parts. In some cases, entry level carbon fiber bikes outfitted with a Sora groupset and upgraded to Ultegra, and then sold the old groupset as new-pulls. It was easier before most companies shut down international shipping of groupsets.
Nonetheless, as many people have mentioned, it may be a losing battle with parts prices higher than you might expect.
The bikes you found:Supercycle Circuit has a "high tensile steel" frame, which means it is scraping the bottom of the barrel. No amount of polish will make it look nice.
Triban RC100 has an Alumunim 6061 frame. But, in many cases those frames are just as heavy as steel.
One option to get into road bikes is to go used. Look for a former top of the line bike, 10 to 20 years old, and with some luck you'll find one for less than your department store bikes. Then if you wish to upgrade a few parts to more modern standards, then knock yourself out.
Even purchasing a 30 to 50 year old frame as a starter, and you may be better off than the department store bikes above... if you're careful. And, the bike will have a tremendous amount of character.