Wrike seems to be a really simple well-designed project management tool that appears to have focused heavily on User Experience (UX). The interface is lightweight, and elegant and onboarding and feature exposure helpers are available but unobtrusive. From the creators: "Wrike is a digital work management tool that lets users track and coordinate projects, combining a simple user experience and interface with enough depth for power users." Honestly, I'd say give it a shot. It appears to apply KISS and although it leans on Microsoft's 365 suite for most of it's business document integrations, it seems really well done.
ToolWrike
By Wrike, Inc.