A lot of things a human can do can be found in other species, but I think the ability to read and write arbitrarily complex ideas really does set us apart, and caused a phase transition. It allows us to transmit ideas across time and space that would otherwise be lost. It allows the accumulation of knowledge that no brain is large enough to hold. Outsourcing our memories to persistent storage. Someone can write down an idea, it can be forgotten for hundreds of years, and then rediscovered and applied. It can allow one person to design something, and communicate that design to thousands of other people. Take that away, and local achievements in knowledge remain local until they are forgotten because other knowledge has takes precedent.
A beaver might instinctively know how to build a dam because it's built into its DNA, but a human can read the writings of past dam builders, learn the abstract theory of dam building, come up with their own improvements, debate those changes with other people interested in dam building, communicate their design to dam builders, and publish their work to become a permanent part of dam building literature. For a beaver to change how it builds dams, it would require a change in their DNA to pass on to future generations.
A beaver might instinctively know how to build a dam because it's built into its DNA, but a human can read the writings of past dam builders, learn the abstract theory of dam building, come up with their own improvements, debate those changes with other people interested in dam building, communicate their design to dam builders, and publish their work to become a permanent part of dam building literature. For a beaver to change how it builds dams, it would require a change in their DNA to pass on to future generations.