Do you also have a Desktop App (ArcMap or ArcGIS Pro)? I hope the ArcGIS Online account is an organizational account.
For publishing, the user needs a Publisher, Facilitator or Administrator role.
For publishing certain type of image layers (Hosted Tiled Imagery Layers/ Hosted Dynamic Imagery Layers), an ArcGIS Image for ArcGIS Online user type extension license is required.
For details, please check User types, roles, and privileges
In case you have any other concern, please share more details about the workflow you are following.