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If you fell straight down from the height of the orbit of the ISS, by the time you reached the thicker parts of the atmosphere, you would be travelling at around 2 km/s. Unprotected, this is enough energy to raise your temperature by 500 °C, but not all of that energy would actually go into you so you would be a little bit cooler. But suffice it to say, if you have to get off the ISS without a capsule, you’re cooked.
A freefall from space has not been demonstrated. The 40 km jumps done are well below the 100 km Karman line (accepted as the definition of space, but it’s mostly an on-paper thing) and much lower than the 400-600 km orbit of the ISS. The thing about these jumps is they begin at ~0 km/h already in or just above where the atmosphere is significant. If you fall from significantly higher than this, you have a lot of altitude in freefall and the atmosphere is so thin that you won’t slow down enough for it to matter, leading to a very high speed entry into the lower atmosphere.
Baumgartner’s top speed was Mach 1.25. If you fell from the ISS, your speed when you got to where he began his fall would be around Mach 6-8.