What entity, element or approach do you have in your organization that links the separate parts together? And no you the CEO or senior leader does not count (although you do get credit if you assumed that was your responsibility).
HR would like to have that ownership and there is a history in the literature trying to prove and justify their role. But because of the nature of many of the HR functions, governance, performance, compensation etc, it works best as a transactional function.
Enter OD, Organizational Development, which was an attempt to separate out the people part of HR. It has its place as a training, development, mentoring entity but it is typically too people oriented to effectively deal with business strategy.
The PMO (Project Management Organization) in many organizations tries to take the reins and be the unifier. The problem there is that they are used to and excellent at the control of process, timelines and tasks. Unity and connection do not come from control. If it does temporarily it dissolves quickly with lack of attention to people, human nature and disparity of approach and perspective.
It could be a COO role but operations will run into the same versatility constraints as the PMO.
The Corporate Communications function also tries to shepard this role in large organizations. The need for a human touch, fairness, mediation and compromise makes this a bad fit. This function tends to present information with a marketing twist to support branding and corporate presence (even with their internal communications). Stakeholders see right through this veneer and are quick to hit delete buttons on all messages.
What is needed is an entity made up of skills and competencies from each of these areas. A clean balance of business and people, structure and process, method and approach.
and so Change Management
Not change management as it is currently rolled out in most organizations (with a project focus) but change management directly tied to corporate strategy. An entity that is responsible for the understanding, the communication and the compromise needed to connect the first horizontal to shared goals. One that feeds back missteps, successes, insights, ideas and innovation.
With ownership of initiatives by high level leaders and a clear and apparent partnership between the first horizontal and the change entity, trust can be built with employees so that future change is more predictable. Or at least less unpredictable.