To give you an update, so far my analysis indicates maybe five very arbitrarily defined and fluid categories we can apply to evidence of cryptids.

1. Earth origin (archaeopteryx, Denisovan): This is when we have DNA evidence and science acknowledges the entity but there's still some difficulty about placement and interpretation.

2. Probable earth origin (dragon, yeti): This is when there isn't DNA evidence but the evidence still treats the entity as a relatively ordinary species that replicates on earth like others; these are distinguishable because the realms where such probable-earth creatures live is harder to explore by humans, leading to the weakness of evidence.

3. Alternate origin (sasquatch, chupacabra): This is when all sightings have an apparent inexplicable cover for them in the sense that the creature doesn't act natural, appears usually one at a time and only in unique incidents, and isn't tracked to a living population on earth like others are assumed to be. This phenomenon is better explained by teleportation of such a creature at occasional times and places from an unearthly source than by such a creature having an ongoing population in the wild.

4. Simulation (grays, reptilians): This is when the phenomenon of regularly inexplicable cover is present and the incidents also take on an unnatural experience that appears extradimensional, hypnotic, or otherwise unearthly. This is best explained not by any physical cryptid but by a simulation of a given form by a nonphysical entity that ordinarily has some other form (e.g. energy patterns that resemble UAPs).

5. Shapeshifting (nephilim, werewolf): This is when the being takes multiple forms, typically a known one (human) and an arcane one (reptilian). This appears to be similar to simulation as above, except that the entity is physical but still retains power to simulate the additional form. Unlike the other cases, these appear to require the concession of ordinary human rights because the entities are subject to the weaknesses of humanity, but they can also be judged independently on their actions as humans. I hesitate to say much here because there should be no slippery slope to generic disregard of humanity because some of them might be something more or less than others.

It seems there is a general pattern in nature that living beings, sentient or not, are classed into independent species or kinds that each develop from seed form during an immature phase, and therefore any being can be classed in a given species according to its origin. Interfertility is the usual mark. If this were not true then a temporal being would exist without any default species that would be regarded as a conglomeration of many or all; but no beings come into existence in record or observation with this phenomenon. So since we are asking about multiple forms it seems that an instance of a being must be classified according to the form it takes from its origin (parent(s)); and that other forms are then secondary, learned from observation of those forms and from power to manipulate one's resonance in this world (physical or not, or both) so as to reflect those forms.

I know that doesn't answer your question, it's just an attempt to begin classification of the question. This is also not to focus on sentience or nonsentience. You seem to be using category (1) as evidence of evolution, and that's an old debate where I gave the hints of an answer, in that the DNA barcode of all species within Homo is the same, so marks of "primitivity" or "development" do not disprove creation. More to the point you use it, and the origin of Pan as well (chimps), to ask about evidence of other sentient races; and it might be used for a long inferential chain, but I don't think we'll find new sentience in category (1). So I inferred the other categories based on the type of evidence we have and the likelihood of different origin methods. (2)-(3) speak of the physical only and cover most of the nonsentient cases, but can include the sentient; (4) is more where we'd put demon testimony, and (5) is more where we'd put shapeshifter testimony ("reptilian" has been used to speak of both, as well as of the chupacabra in group (3)). And in particular (3)-(5) have in common that they are not hiding in earth but that they have pathways to earth from elsewhere. (Some might put them in the volcanos and the hollow earth, but my theorizing is functionally equivalent with that when I speak of not being in the explored earth. Wherever they arise does not follow known physics, which explains why it becomes hiding rather than the trackability of groups (1)-(2).)

You allude to the possibility that the cryptid is also modifying the perceptions of others. I don't rate that option highly, but I must keep an open mind. I don't think we're modifying light for those who are fully awake and using their eyes normally, but I do think that there are powers of hypnosis that transfer imaginative forms into the place in the mind where sight is understood. But I'm not treating any of these events as imaginative. If an abductee reports an experience that is better explained as hypnotic than as physical, that doesn't teach us about form (except maybe energy form). The question is limited to experiences that indicate species of creatures that recur in other experiences, not about hapax visions.