what was blitz crank before he was forced into support?

They intended him to be a top laner I believe.

nobody forced him into anything. Blitz support is the result of everybody copying the pro's. And since the pro's typically played him as support and nothing else, a bunch of sheep decided he only belongs there.

Blitzcrank can do any position.

There wasn't really lane positions back then. I think in general, he was suppose to be a "fighter" back then

In the earliest days of League, the roles were less ingrained and not as rigidly established. "Support" wasn't what it is today - they didn't have special items or their own source of gold generation. It wasn't even a common practice to force the "Support Champ" not to CS and let the ADC take it all. Junglers were also less of a Must Have for many of the same reasons - no unique item paths, less gold. It was common not to have a jungle, or only one team to have one. Mordekaiser back in the day was a famously strong 1v2 laner. Nasus, on the other hand, wept in that lane.

Even a Jungle Champion and a "Support" Champion became more and more common, it was still a long time before they had the handouts they do today. In both cases, the Champions who would succeed the best in these were Champions who were not as reliant on gold or items, but were rather quite strong purely on their abilities and what they brought to a team. Warwick was a strong jungler because he didn't really need items; his job was to click R and pin down a target. Similarly, Blitz did not need a lot of items, he was/is/will always be strong because of the utility his hook brings. So while Blitz used to be able to mid/top as either AD/AP, he wasn't really designated as a "One Lane" Champ.