Lately I’ve been dealing with a lot of ransomware cases. And often our team runs into issues with the IT staff from the victim organization.

What is the most common way companies get hacked? How often is a good old dodgy email the way hackers gain access to a company's systems/storage?

Lately it’s been vulnerabilities in edge devices like VPN concentrators and firewalls. Also on-prem Exchange servers.

How much does relying on email as the primary method for a company to communicate both internally and externally affect their vulnerabilities - as a rough %. In your expert view?

Honestly not much lately. Attackers are preferring to use direct exploits rather than social engineering.