maybe the aliens are so advanced in a civilized way to value life , and are so technically advanced that they know they can destroy us easily, yet not without our savage paranoid little minds causing some type of conflict with them in which we could cause them Some harm, maybe not destroy them and protect ourselves. But they don’t want conflict at all and they wait and watch until we won’t cause a incidental conflict if they did present themselves.  so maybe we are the reason we haven’t seen an actual alien or even there evidence(signals,or craft).  maybe there protecting us from our underdeveloped nature, not in a parental way but in a generally decent , benevolent manner.  Idk. just a thought