Inputfields are quality content in ‘the web’ world, they send valuable information from the guest to the server. Some inputfields are repeatetly used very often with different inputs. If you have extensions or browser software that autocompletes the fields this can be very annoying. To turn autocomplete off simply set autocomplete to false:

<input type="text" name="email" placeholder="Email" id="email" class="first-element" autocomplete="off">