What would happen, if we encountered a less advanced alien species?
We succeed in developing FTL travel, and go exploring. One of our exploration ships finds a planet with a sentient race, but one that is at about the equivalent of say, early Homo Sapiens. Stone-age technology. Perhaps fairly bright, but 200,000 years behind us technologically.
I would imagine that the scientific community would demand a "prime directive" sort of approach. Strictly hands off. Observation only.
Any contact whatever with such beings would be potentially very dangerous to them.
On the other hand, we "advanced" humans have a long history of exploitation of less-advanced peoples wherever we encountered them. Columbus, on making landfall, remarked how peaceful and compliant the natives he encountered were, and that they'd make excellent slaves.
Would we try to be on higher moral ground? I think much would depend on what resources were available on the planet.
To us? It will confirm the existence of alien life - this will ruffle the feathers of our understanding, and there will be some upheaval considering our religious attachments, scientific misconceptions, etc.
To the Alien? If they are very lucky, we don't depend on the same resources as they do. Their planet is useless to us, and we merely have cultural exchange (assuming they are advanced enough to have language).
If they are too much like us, their planet will become our colony.
Possibly some combination of these could make them useful to us, but not their planet. Like if they don't use oxygen, but they tunnel through rock, or if they are naturally radiation shielded. In that case some sort of symbiotic relationship is possible.
In general, their prospects are not good.