I need to disagree with @AlexanderWoo: in my experience, at high-ranking journals, "interesting enough for the journal" is something that the editor generally decides before sending it out to reviewers, which is why most papers at such journals are rejected without review. Enthusiasm is not needed from peer reviewers, just a scientific assessment of the results.
Thus, I suspect that you are instead dealing with one of two other cases:
- Those six comments actually included something the editor considered quite serious, even if you did not. If a paper is fatally flawed, it may not take many comments to state the flaw, and major issues sometimes become invisible to an author because they are too close to the problem.
- The editor is being lazy and sloppy somehow in their handling of the paper. Even if the reviewers hated your paper in hidden fields, the editor should normally have explained the decision in at least an abstract fashion (e.g., "not appropriate to this community", "not significant given the citation from reviewer 2").
Note that in both of these cases, a reviewer's assessment of significance (or lack thereof) may cause the editor to reassess their level of interest in the manuscript. Again, however, what is required to pass is not enthusiasm but merely finding that close examination of the paper does not invalidate its claimed significance or results. In both cases, however, such a reassessment should be clearly reflected in the comments of the reviewers and/or the editor.
You can distinguish between the two by writing to the editor for a more thorough explanation of the reasons for rejection, politely explaining that you are not understanding the reasons for rejection and wish to improve your paper. You will almost certainly be unable to change the editor's mind at this point, but you may learn what (if anything) needs to be changed to give your paper a better chance at the next place you submit.