In the light of international treatment and the established jurisprudence of public international law, an individual is still not seen as a subject of public international law.
The International Criminal Court should make it a priority to guarantee that all individuals are seen by the global community as subjects of public international law.
According to Rome Statute of ICC its jurisdiction ratione personae is limited to natural persons (art. 25), and legal persons are expressis verbis excluded from ICC's jurisdiction. This rises the question of legal persons' status in international criminal law. I think that in this sense is very interesting a decision of Special Tribunal for Lebanon where it decided, that a legal person (not only natural) could be punished (see e. g. https://www.researchgate.net/publication/322314512_Criminal_Responsibility_of_Legal_Persons_Introduced_by_the_Special_Tribunal_for_Lebanon). It is a question if there was not this explicit limitation in art. 25, ICC's jurisdicion would cover also legal persons (corporation etc.)?
However sorry, this is rather another question than an answer.
The ICC is still an international agreement, and it is between States. The right to make laws, such as criminal ones or even those in terrorism, are highly SOVEREIGN and very few states will allow authority for same to transfer from the state to some supreme international authority. Have no doubt that every nation out there wants to keep its own power, but wants other nations to give up theirs. This is realpolitik. All argument to the contrary is subterfuge and at best lex feranda and not lex lata. Thus, there will always be that buffer of the state as enforcer between the international community and State-aligned individuals. As an example, military powers that believe in military interventions (which are sometimes justified - think USA’s involvement in WWII) cannot let the ultimate authority over their Generals pass to an outside source - or much would not get done.
This seems like the authorization of impunity. However, honest Nations trying to do good, often with international or coalition consensus, are assuredly doing right much of the time. The “other side“ of that action will always cry ‘foul,’ but hopefully more often than not, the action is best for the greatest number. History often shows that interventions had cause or were right. (This does not disregard the risk of revisionist history).
The short of it is that there will always be an ‘us’ and a ‘them.’ The ‘us’ will form governments. Those governments will not give up control - but they can be negotiated with and encouraged to do the right thing.
Ask yourself this...do you want a single world power with complete authority? Like an ICC with full international jurisdiction? Even after it becomes dominated by others who disagree with your views (and possibly, your needs)? Better to keep some checks and balances.
The ICC has a problem: States that commit genocide do not want to be members, States that could be charged with genocide are not placed before the court...only individuals, and if the ICC can't identity perpetrators of the genocide (note its reaction to the Islamic State) then it freezes in its tracks and fails to act. These are significant limitations when since 1945 there have been at least 185 probable genocides and few if any have been recognized as crimes against humanity.
ICC, INTERNATIONAL CRIMINAL COURTS, to my account ,its activity is linked with criminal CASES, having ramifications and two or more States/NATION'S ... which is a CITIZENSHIP person's criminal CASES having overlapping with other countries...
."...In the light of international treatment and the established jurisprudence of public international law, an individual is still not seen as a subject of public international law..."! The individual of a Nation, will be taken as SUBJECT of the ICC only the case is required to be referred to this Court, THROUGH some other Nation...In my reading,all individuals of the GLOBAL SYSTEM nations can't be made as subject of ICC, UNLESS AND UNTIL there becomes GLOBAL CITIZENSHIP ...PERSON'S of any country can move anywhere to anywhere, WHICH is is a NIGHTMARE BEFORE THE PRESENT OF POWER ,POLITICS, or in short POLITRICS play games for individuals power and authority...