People have different interests and different outlooks. Conflict and disagreement is the normal state of affairs in social life. Democracy is, among other things, a way of managing disagreement and forging cooperation out of conflict.
In autocratic systems, the social good is defined from above and people have a duty of obedience to the ways and means that are imposed upon them. Autocratic governance depends on a pretence of agreement and therefore the repression of disagreement.
Democratic governance is grounded in an acceptance of disagreement and an ideal of cooperation without repression. To get on in society, we need agreed upon goals and procedures on many matters, some of which are controversial, say the always contested business of taxation. There is no such thing as a public policy that is the preferred policy of everyone, and there is no such thing as a public policy that does not come with a cost to someone. In a democracy, ideally, everyone is entitled to state their views and to defend their interests vigorously. At some point, however, a shared position needs to be found somewhere in the landscape of disagreement. That can be done democratically, for example by voting in a national assembly, or in a general election or a referendum. Some citizens will unavoidably be disappointed in what becomes the shared position, since it will not be their preferred position. The ingenuity of democracy is that since everyone has had a say in the debate and procedure leading up to joint decisions, or the opportunity thereto, everyone should be able to accept the outcome, even when it is not their preferred outcome. The access to discussion and deliberation is conducive to willing collaboration.
When this works, on the one hand society is able to get on with it and move forward, and on the other hand no one has been trampled on and humiliated. Democracy, then, is a method for peaceful resolution of conflict and for collaboration with dignity.