Good question. I think it comes down to the reverse of the greatest commandments to love God and love people. Anything that is essentially worship of a false god (greed, lust, pride) is sinful. And anything that results in unloving treatment of people is sinful.
Good point. That reminds me of a point I heard by a certain psychologist that might lead me to formulate the following definition: all people have values. These values have relative degrees of importance to the individual, and this is constantly proven: at any given time, there are many things you could be doing. By choosing to do one of them, you have given it a higher value (at least in the current moment) then other possible actions/values. Thus, everyone has a hierarchy of values. In Christianity, God must always be on the top of the hierarchy of values. A sin is when something, in the long-term, short-term or just current moment, is when you displace God at the top of your hierarchy of values with some sort of other goal.
God created all humans and has made them special - each one with intrinsic value. When yous murder someone, you have murdered someone created by God’s image. You have placed your personal vendetta over the intrinsic value God has endowed the human with. When you get drunk, you’re placing your drinking above God. Obviously anything could happen when you’re drunk, including many either forms of sin. You could damage yourself, others, or you’re contributing to a drinking culture that can harm others. Etc, etc.