My knowledge of adhuc is that it is typically used in the context of some continuing action. For example, in the story of Perseus, it reads:
[Acrisius] autem ubi Perseum vīdit, magnō terrōre affectus est; nam propter ōrāculum istud nepōtem suum adhūc timēbat.
"However, when Acrisius saw Perseus, he was afflicted with a great fear; for on account of the oracle he still feared his nephew."
So, in this use we have a situation where stuff has been going on for a long time, and the uncle STILL fears his nephew. However, in the following passage (also from Fabules Faciles) adhuc seems to be used in some other way:
Herculēs, Alcmēnae fīlius, ōlim in Graeciā habitābat. Hic omnium hominum validissimus fuisse dīcitur. At Iūnō, rēgīna deōrum, Alcmēnam ōderat et Herculem adhūc īnfantem necāre voluit.
"Hercules, the son of Alcmena, once was living in Greece. This one was said to be the strongest of all men. But Juno, the queen of the gods, hated Alcmena and still (???) wanted to kill the baby Hercules.
So, in this context adhuc seems to make no sense. It is the beginning of the story, so still since what? Apparently adhuc is supposed to mean something else in this context, but I can't figure out what is meant by it.