A common misunderstanding is that Buddha taught "life is suffering". As Mr./Ms. AS pointed out, there is often an overemphasis on  suffering, but actually in Buddhism, there is only suffering when there  is appropriation and clinging. To be clear: Buddha has never said "life is suffering", however, he did teach right from the beginning in his first discourse on the four noble truths that "appropriated aggregates are suffering", and by appropriated I mean tainted with I-making and mine-making.

In the Pali suttas, clinging and appropriation are not equated with the sheer aggregates ( https://www.dhammatalks.org/suttas/MN/MN44.html ), and as Stian mentioned, he thinks aggregates are almost never mentioned in the sense of 'sheer aggregates' in the Pali canon. I think you get glimpses of how are 'sheer aggregates experienced by Buddha/arahants' in scriptures like Bahiya Sutta and Kalaka Sutta. In any case, the appropriation is what causes suffering, and the end of appropriation is the end of suffering.

Here's some nice clarifications on Dhammawheel:

Thusness wrote in 2009:

‘Psychological pain’ is directly related to our ‘sense of self’. The sense of self is directly related our deeply rooted ‘inherent and dualistic thought’. This pain is an indication that we have not fully recognized the cause and many faces of the arising ‘sense of Self/self’ and that includes the attempt to remain as an unaffected passive observer. If we prescribe the wrong medicine, then there is no cure. Therefore your experience that “remaining as a detach observer doesn’t seem to eliminate the pain and anxiety yet breathing exercises and some physical exercises do” is a precious realization. There are 2 parts to it.

First we must realize why we equate ‘detachment’ to this ‘unaffected and passive observer’. It is due to an incomplete insight of our pristine yet non-dual and empty nature of awareness. It is partly due to our direct and non-conceptual experience of our “Unborn, pristine and luminous nature “of awareness and partly due to the karmic tendency of solidify experience. When this direct experience is understood from the lens of a ”dualistic and inherent” framework, it is natural that we view “a passive observer” as the way to solve this psychological pain.

Second, in addition to the ‘unborn, pristine and luminous’ aspect of awareness, we must have a more thorough and deeper insight into our ‘intimate, inseparable, non-dual and dependent originated’ aspect of Awareness. This relates to why “breathing exercises and some physical exercises is able to relieve psychological pain". We must directly and deeply experience what is meant by “inseparable” from the transient and understand “beingness” is never apart from whatever arises.

Lastly what that is ‘unborn, pristine and luminous’ cannot be “dependent and inseparable from the transient” appears sound only logically but not experientially. It will first seem illogical and unnatural to accept such an idea, but when the tendency to dualify and solidify experience subsides, then scenery, taste, scent, sound, breathe, the sensation of our feet touching the ground…all arising will help lighten this psychological pain. Therefore fearlessly, unreservedly and completely open to whatever arises.