Approx. 68% of all projects fail because of at least one of the three target values for project success (time, costs, quality).
(Chaos Report 2009)
The ten knowledge areas of the PMBoK (Project Management Institute, 5th edition) are fundamental to prevent such a failure. People-oriented questions play an important role. Think of communication management, stakeholder management & HR management. But also for all other subjects: Keep an eye on the well-being of the people involved. (see also: “Peopleware” by Tom DeMarco)
It does not matter whether you are running agile software development (Scrum) or according to the classic waterfall model.
The mastery of the 10 areas of project management knowledge and the orientation of the participants bring you into the 32% of successful projects.