I think it's very unlikely to expect all aliens to be humanoids, there are plenty of viable alternatives, and a few billion years of evolution on earth has produced a few nice examples.
Take the crab or the octopus for example, they have body structures that are very different from humans, and they don't even have a head that's seperate from the rest of their main body, they also have a number of very usefull manipulator limbs.
What if evolution had gone differently, it is a game of chance after all. What if crabs had evolved into warm-blooded creatures millions of years ago, and mammals had not? Would those crabs have evolved into having four limbs, and would they have started walking on their hind legs? unlikely. If you look at evolution it seems like that when a certain design is succesfull, it becomes hard to change. All insects have 6 limbs, and all mammals have 4, even though some insects and mammals may have started using those limbs in very different ways. If you would rerun evolution on earth the outcome would likely be very different, and whatever creature would have evolved intelligence, it would be unlikely to look like us.
Back on topic, great drawing Jarena, I'm really looking forward to the non-humanoids you can come up with
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