The only speculation that denies an aircraft, is overzealous people who can't believe in that maybe these lights we see, are actually created from real objects. These objects are not by fantasy, and all logic would assume that such objects, acting in very symmetrical fasions, have behind them a control of intellience.
This intelligence must then result in a theory which explains some kind of sentient being behind such lights.
All of this, by logic alone, reolves to two types of explanation:
1) That man is behind them
2) That some other intelligence is behind them
Take your pick, as the OP correctly gave.