That mean chakra is needed to create a chakra for all human. Okey.basically people had physical energy and spiritual energy, but lacked the means to connect it. When they received chakra from Hagoromo they used it to connect the two energies and amplify their power creating chakra.
So Kaguya was the first to have charka, everyone else only had the raw materials with no way to connect them. If IT connected their two energies then Kaguya could actually use even ppl then as her own chakra factories just like she did when BZ resurrected her.
In IT Kaguya channeled her chakra into human body, created a chakra and suck it out.
That can explain how someone without chakra still can be put inside IT and cocoon.