Consistent navigation is a part of the Web Content Accessibility Guidelines and is covered by Success Criterion 3.2.3. Providing consistent design and navigation aids in understanding and predictability decreases the amount of time users have to spend searching for information. Course organizaiton should be consistent, logical, and efficient (reduce the number of "clicks" required to get to any point in the class). There are a few things you can do to ensure that content is consistently presented in the same manner.
Quality Matters (QM) cites the ability to easily navigate a course as one of the first indicators of a quality online course because the less time students need to spend searching for content, the more time they can spend learning the content. Providing students with clear instructions on how to get started in the class also reduces the likelihood that they will overlook critical course components such as submission instructions and due dates which creates a better overall experience for students and faculty alike.
Much like the use of headings aids users to quickly and easily find information in documents, having consistent names and visual tool indicators helps all students quickly and easily find information within a course shell. If you do not add or change any icons within Blackboard, you shouldn't have to worry about this element as Blackboard tool icons are consistent across the entire platform.