Just looking into the dialogue by Plutarch "De facie quae in orbe Lunae apparet" and my impression is, they knew the law of universal gravitation quite well.
For instance, it is argued that
- A body thrown to the center of Earth will oscillate around that center due to its momentum. That masses of a thousand talents weight, borne through the depth of the earth, stop when they reach the middle point, though nothing meets or resists them; or, if mere momentum carries them down beyond the middle point, they wheel round and turn back of themselves (...) That water rushing violently downwards, if it should reach this middle point— an incorporeal point as they say — would stand balanced around it for a pivot, swinging with an oscillation which never stops and never can be stopped.
- All things on Earth attract to each other. And yet if every weighty body converges to the same point with all its parts, the earth will claim the heavy objects, not so much because she is middle of the whole, as because they are parts of herself.
- The same should happen on other bodies, including the Moon and fiery bodies like Sun and the stars. If there is any body neither assigned originally to the earth, nor torn away from it, but having somewhere a substance and nature of its own, such as they would describe the moon to be, what is there to prevent its existing separately, self-centred, pressed together and compacted by its own parts? (...) For it is not proved that earth is the middle of the Universe, and, further, the way in which bodies here are collected and drawn together towards the earth suggests the manner in which bodies which have fallen together on to the moon may reasonably be supposed to keep their place with reference to her.
- The distance to the stars is beyond measurement capabilities greater than the distance to the Moon, and the distance to the Sun is at least 80 times greater. She is lower than the stars by a distance which we cannot state in words, since numbers fail you mathematicians when you try to reckon it, but she touches the earth in a sense and revolves close to it
- The distance to the Moon is (by highest estimate), 56 times the Earth's radius (which is quite precise).
- The Moon is so much close to Earth that it nearly "touches" Earth and affects by its gravity even things on Earth: For she often fails to clear the earth's shadow, rising but little, because the illuminating body is so vast. But so nearly does she seem to graze the earth and to be almost in its embrace as she circles round, that she is shut off from the sun by it unless she rises enough to clear that shaded, terrestrial region, dark as night, which is the appanage of earth. Therefore I think we may say with confidence that the moon is within the precincts of earth when we see her blocked by earth's extremities. (...) Upon this basis, the distance of the sun from the moon works out to more than forty million three hundred thousand stades. So far has she been settled down from the sun because of her weight, and so nearly does she adjoin the earth, that, if we are to distribute estates according to localities, the 'portion and inheritance of the earth ' invites the moon to join her, and the moon has a next claim to chattels and persons on earth, in right of kinship and vicinity.
- It is also claimed that life on the Moon is impossible due to thin atmosphere, no water and hot temperature: Then as to winds and clouds and showers, without which plants can neither receive nor maintain existence, it is out of the question to conceive of their being formed, because the surrounding atmosphere is too hot and too rare.
So, my question is: can we say that scientists at least hypothesized the law of universal gravity? Can we say that the possibility of atmosphere on the Moon was hypothesized, and it was considered too hot and thin to support life? Can it be said that this work more or less reflects the scientific consensus or mainstream views of the 1st and 2nd centuries?