Odd. I bought HiB 6 back in the day, and the higher tier (there were only 2 that I can tell) has two keys - one for Dustforce by itself, and the second key was for Wizorb, BIT.TRIP.RUNNER, Gratuitous Space Battles, and Jamestown all as one Steam Key. So, what's been described by the giver.

Not 100% sure what's in this one

Isn't that what the Indie Game Bundle site is for, though? At least for older bundles.
Wikipedia listed later ones (though I think IGB added them in later on, as well), and SG is reliable enough on ones after that, after Rachel and Shakti took over. / https://indiegamebundle.fandom.com/wiki/The_Humble_Indie_Bundle_6

IGB, much like Shakti's threads, is usually really good about listing special circumstances (though Shakti's threads have the further benefit of listing historical low [on BTA] and region restrictions). Also worth noting that earlier Humble Bundles added a lot of games in after-the-fact, which may account for some variations in recollections.

In this case:
"Those who purchased before Sep 25 or beat the average [after Sep 25] also received a key [on or following Sep 25] for Bit.Trip Runner, Gratuitous Space Battles, Jamestown, and Wizorb."

The issue here is:
"Purchasing this bundle for at least one dollar included a single Steam key that would activate Rochard, Shatter, Space Pirates and Zombies, Torchlight, and Vessel on the purchaser’s account. Paying more that the average added one more Steam key for Dustforce. "

Neither the BTA nor the single tier games appear to be included in this giveaway, which means that even if this is just for the BTA tier and not inclusive to the first tier, or even if it's switched to the first tier, neither seems to match SG expectations for the giveaway format.

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As a follow-up note, Barter.vg has pretty much entirely replaced sites like ITAD and Salenauts as a good resource for checking Bundle details, though- as with the two other sites mentioned- it can be a bit lacking [compared to SG threads or even just IGB] on details (such as pricing or special circumstances). While that pretty much puts the sites on par with one another, Barter has the advantage of being a lot more reliable in comprehensively listing bundles, whereas the other two sites often overlooked many (especially from smaller sites or Groupees).

ITAD is of course still better when one wants to check price history, or psudeo-bundles.

When everyone is above average.
Average: Am I a joke to you?