Personally, I think that Hellenistic art had a very progressive take on Greek humanist values. In earlier artwork we have seen a lot of focus on the gods and the human place in relation to creation and the gods. In Hellenistic art, there seems to be more focus on humans in relation to humans. With this I mean that we see more focus on various components of humans, such as moments of serenity or moments filled with strong emotions. In short, there seems to be more focus on the range of human emotions. For example, we have the sleeping cherub, which seems so lifelike and realistic. It is almost as if it was depicting an actual child. Then we have the Laocoon, that have strong emotions of fear and desperation. These emotions are so vivid, which I would think is highly progressive towards humanist values.
The only reason I would think that Hellenistic are can be seen as regressive is that there is less focus on the gods or nature. Maybe there are humanist values that focus on what a human is in relation to nature or spirituality, and choosing not to focus on this can be seen as different. Religion often gives humans a purpose, and choosing not to focus on the human value according to religion can be seen as taking the purpose away from humans. I could see how this would be an opinion of regression.