Complacency against weaker side is Indian mindset (unless/until you are experienced and don't take anyone lightly) and this match is no way reflection of skill in the squad. The team will certainly come back strong after this defeat.
you're right, big teams often fail against weak teams because they take them too lightly. This is a brand new Indian team that is inexperienced and that's why they failed against a weak team in Zimbabwe. Zimbabwe even didn't qualify for the World Cup but India is the World Cup winner team So that defeat will teach a lesson