SpaceX started with the business plan of low cost, mass producible single use launchers. Falcon 9 was not designed with any level of reusability in mind. There was a major redesign to add landing hardware, but the whole reason for Starship being a totally new design was the reusability that a Falcon "super-heavy" derivative could never achieve.

Good point! I don't think Falcon 9 is large enough for full reusability.

I don't think Stoke's first vehicle will be large enough either (beyond proving out the technology). They will eventually need to build a much larger one.

They tried to use parachutes to slow the boosters down on the first two flights. Turned out it didn't work: the boosters burned up/disintegrated before the parachutes could deploy.