Why wood aliens by necessity be highly advanced beyond human technology?
We could get THERE right now. It would take a huge effort, but such a craft was proposed decades ago using propulsion powered by atomic bombs. Project Orion if I recall correctly.
Imagine a civilization like ours facing planetary destruction for some reason. Or they’re just expansionist or it’s a splinter pirate group, whatever. They send a generational mission, or one with suspended animation. Or a robotic advance guard. There’s no need for Independence Day highly advanced capabilities.