I think the weirdest thing we could find in space would be a species that looks nearly identical to us. It would bring so many questions.
The answer really depends on the history of the planets' evolution. Humanity was 'molded' by significant amount of 'coincidences' through the earth's events, but most importantly are the five major extinction events: 1: Ordovician-silurian Extinction, where small marine organisms died out. Without it, life on land would start one or two million years earlier. 2: Devonian Extinction, where tropical marine organisms died out. Without this, land plants would grow without enemy and jumpstarted the oxygen production, causing the era of giant insects to come faster. 3: Permian-triassic Extinction, basically the 'great dying' where 90% of all organism on earth died of mysterious causes. If this event didn't happen, most of earth's current creature would be some kind of synapsids---a mix of lizard and dog. 4: Triassic-jurassic Extinction, where volcanic eruptions raised the CO2 level in the atmosphere and killed 76% of all creatures living on earth. This enables dinosaurs evolve larger because there's no 'larger' predators on earth on that time. 5: Cretaceous-tertiary Extinction, the most known event of Ice Age following the meteor impact that killed all the dinosaurs. Without this mammals would be mostly be rodent-like and dinosaurs would rule the surface world.
Humanity's predecessor *just* happened to survive through these 5 major (and 15-16 minor) extinction events to give birth to us humans. If there's any other extraterrestrial species that somehow looks like us, then the only possible explanation that scientist could give would be 'someone or something guided the events leading to this species' evolutionary process to MAKE them look and function like humans.'
Because we know CRAB is the most evolutionary-perfect form for crustaceans on earth, yet humans, anatomically and physiologically speaking, are among the worst designs for any animals to evolve to, with all-around weaknesses. Humans ONLY managed to be the most successful animal on earth because we are able to both make and use tools to make up for their overall weaknesses, plus they can pass down 'knowledge' to their descendant, meaning they will never start from 'zero', unlike other animals.