Looking at how it's attached to the joists, looks like bolted through 2 2x6's, back when a board was actually 2" by 6". The bolts are offset from the joists so possibly connected to a piece of angle bolted above. Designed to hold some weight beyond the weight of the contraption.
The base and "upright" section look like it came from an old radial arm saw. The u-channel coming off the upright looks like a davit that's upside down. The round pipe piece looks more like a handle and there looks like a roller or bearing between that plate and the davit. Rotated about 180, the eyebolt could be used as an anchor for a pulley or small hoist to get something from floor to bench level. That's what I would use it for. [emoji848]
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