Who was/were first one(s) to recognize that what we see in the night sky are not just points of lights but full blown lands(in case of moon and some planets) and so on? I am guessing it would not have been possible before telescopes.
The plurality of worlds had been discussed since ancient times, but there was little evidence, and the other worlds were not necessarily imagined to be the planets. The ancients had some idea of the relative sizes of the different planets' orbits (around the earth), but they had no way of tying these to any absolute distance scale, so they didn't know how big the planets were.
Galileo was the first to resolve the disk of Jupiter, detect the moons of Jupiter, and observe the phases of Venus. The phases of Venus implied that it was a sphere and that it circled the sun rather than traveling on a geocentric epicycle. The motion of the Jovian moons was seen as a challenge to Aristotelianism, since according to Aristotelianism they should have followed their natural motion rather than being affected by Jupiter. From an Aristotelian point of view it wouldn't make sense to imagine, for example, an explorer standing on another planet. The explorer would have fallen back to earth.
Although the moon has features that are clearly visible to the naked eye, apparently it was believed before Galileo that these were markings on a perfectly smooth surface. Galileo observed the moon telescopically and published a description of mountains and craters. Through a telescope you can see that shadows are being cast.
Once Kepler's laws had been found, and the apparent angular sizes of the planets measured, it became possible to find the sizes of the planets in comparison with the earth.