With Blender 2.8 the ability to use a more conventional left-click selection mechanic is possible. Although right-click might still be set as the default (see below), being able to swap mouse buttons brings Blender in-line with practices common, and more familiar, to other applications.
Design note: Blender may install with right-click as the default if a previous version of userpref.blend is found. See “Fresh Install” note below for remedy or follow the remaining instructions to switch selection.
Fresh Install/First (re)Run
If Blender 2.8 is installed fresh, i.e. no prior versions of the applications are in use or available, Blender will present a Quick Setup splash screen  when starting. Here the Select With option can be set, either as Left or Right, by clicking the appropriate button depending on personal preference. This will then be saved to userpref.blend which loads each time Blender starts.
Design note: if other versions of Blender 2.8 have been installed the Quick Setup screen will not appear because selection preference is either using an old default (right-click) or it may have been previously set and saved to userpref.blend found in C:\Users\[user]\AppData\Blender Foundation\Blender\2.80\config\. If this is the case deleting or renaming the file will force Blender to regenerate the *.blend based on the Quick Setup options established during first (re)run.
When Blender 2.8 is (re)run for the first time a Quick Setup  version of the splash-screen appears providing the opportunity to set Left or Right click as the default selection action which is then saved and used each time the application is used/started.
Setting Left Click
If the selection preference has been previously set and/or a change is needed, to set left-click as the selection default, first access User Preferences from the main Edit menu in the Info Editor (Edit » User Preferences). This opens the preferences window.
Design note: User Preferences is where most, if not all, the settings and options that determine Blenders general behaviour, how it works, are changed or set, saved to userpref.blend.
Next, in the Blender Preferences window  that appeared, click Keymap  to access associated options. Here, under Preferences, are the Select With options; the Left and Right  buttons. Click Left  to set left-click as the selection default. Close preferences to then be immediately able to select objects using the left-mouse button.
Design note: once Left-click is enabled, selecting multiple objects can be done as normal engaging the Shift key (Shift + left-click), right-click and all associated functions will be disabled or transferred to left-click.
Important: if LEFT-click is set as the selection default it may disable or interfere with other operations and function associated with the left-mouse button, e.g.Ctrl + left-click drag will no longer Lasso Select.
To set left-click more permanently as Blender 2.8’s default selection mechanic, after clicking the Left button, click the Save Preferences button bottom-left to store the change in the (*.blend) start-up file thus ensuring left-click become the default action for new projects.
Design note: loading older projects may require left-click to be set per the above because settings may be brought in from the *.blend file originally used to create the project and not the updated start-up file. Setting left-click should then be stored as a preference along with others the project may contain/include.
Setting left-click as the selection mechanic for Blender 2.8.